In diabetes management, compliance to specified insulin regimen is important, i.e. compliance to insulin injection time schedules.
For diabetes patients, the daily injections become routine, and it is been found in various end-user studies, that diabetics sometimes are in doubt whether or not an injection has been made, or even forget to make an injection. This uncertainty about last injection makes the diabetic uneasy and in worst case leads to an additional injection with the risk of hypoglycemia.
It is known in the art to provide an injection device comprising means for indicating the time elapsed since the last ejection. An example of one such injection device is known from U.S. Pat. No. 5,645,534 which discloses a medication delivery pen having an indicator that displays the time of the last injection through interaction between a cap and pen body. After injection, the cap is replaced on the pen body such that a time of day indicator on the cap is aligned with a day of the week indicator on the pen body to visually display the time of day of that injection. The pen body includes a set of visual indicia around a circumference that represent days of the week and the cap includes visual indicia that represent different times of the day e.g. AM and PM. However, one disadvantage of this technology is that the time of the last injection is represented as a specific time of the day and thus persons crossing time zones have difficulties determining the time elapsed since the last injection.
Another example is known from in the WO 97/30742, which discloses a syringe having an electronic representation of parameters such as magnitudes of the set dose and the latest injected dose, which syringe further has a stop watch, the status of which is electronically represented and is together with the electronic represented parameters reproduced in a display showing the number of hours passed since the last operation.
Further examples may be seen in WO 90/09202, U.S. Pat. No. 6,620,133, EP 0 362 484, DE 102 36 669 and U.S. Pat. No. 5,728,074.
It is an object of a preferred embodiment of the present invention to provide an injection device wherein the time elapsed since the last injection is not relative and thus not sensitive to travelling of the patient across time zones. Furthermore, it is an object of a preferred embodiment to provide a solution which is simple and small enough to be embedded in a disposable pen.
Additionally, it is an object of a preferred embodiment to provide an injection device making it easy to determine the time elapsed since the last injection in dark surroundings. Furthermore, it is an object of a preferred embodiment of the present invention to provide an injection device wherein the power consumption of the circuit signalling time elapsed since the last injection is as low as possible.